The potential uses and recognized advantages of employing electrical energy for surgical purposes are ever-increasing. In particular, for example, electrosurgical techniques are now being widely employed to provide highly-localized tissue cutting and coagulation capabilities in both open and laparoscopic applications, thereby yielding reduced tissue trauma and additional advantages relative to prior traditional surgical approaches.
Electrosurgical techniques entail the use of a hand-held instrument or pencil having one or more working surfaces that transfer radio frequency (RF) electrical energy to the tissue (e.g. via a stainless steel scalpel or blade), a source of radio frequency (RF) electrical energy (e.g. a dedicated electrosurgical generator), and a return path device, commonly in the form of a return electrode pad positioned under a patient or a smaller return electrode positionable in bodily contact at or immediately adjacent the surgical site. The return path device provides a return electrical path from the patient tissue to the energy source. More particularly, both the instrument and the return path device are interconnected via electrically conductive wire(s) to the source of the radio frequency electrical energy which serves as both the source and the sink for the electrical energy to produce a complete electrical circuit. When a hand-held instrument and return path pad are utilized, the electrosurgical technique is termed monopolar. When a hand-held instrument and smaller return path electrode (i.e. selectively positionable at or immediately adjacent the surgical site) are utilized the electrosurgical technique is termed bipolar.
The waveforms produced by the radio frequency electrical source may be designed to yield a predetermined electrosurgical effect, namely tissue cutting or coagulation. In this regard, prior to the present invention, tissue cutting/coagulation effects have been the sole parameters considered in the design of electrosurgical waveforms.
Despite the advantages associated with known electrosurgical techniques, one attendant implication has been that deposits build up on the surgical instrument working surfaces that convey electrical energy to the tissue. The deposits form from matter that is ejected from the tissue and contacts the working surfaces, and from tissue matter that directly contacts the working surfaces and stick thereto. The working surfaces typically heat up as the electrical energy is applied to them, which in turn causes the deposited materials to change their physical and chemical composition. The deposits are commonly referred to as eschar. As eschar builds up and becomes increasingly thick, it progressively detracts from the corresponding electrosurgical procedure (e.g. cutting). That is, for example, the eschar builds to such a thickness that a surgeon must interrupt the surgical procedure to clean the instrument's working surfaces. Cleaning commonly entails the use of abrasive pads that scrape the encrusted eschar from the working surfaces of the instrument. As the surgical procedure continues, the described cleaning procedure must be completed with increasing frequency. Such stoppages for cleaning interfere with the efficacy of the surgical procedure, cause delays and otherwise result in significant annoyance to medical practitioners.
In addition to the use of abrasive pads, other approaches to deal with eschar deposits have been restricted to treating electrosurgical blades with or making blades from materials intended to reduce eschar build-up. Such methods have included electropolishing stainless steel electrosurgical blades. Other methods have included covering the working surfaces with fluorinated hydrocarbon materials (see, e.g., U.S. Pat. No. 4,785,807), and coating niobium blades with a niobium oxide (see, e.g., U.S. Pat. No. 5,030,218). These approaches for eschar reduction still result in eschar deposits and require a focused effort on the part of medical practitioners to remove the eschar deposit from the working surfaces of the surgical instrument. Additionally, such cleaning frequently removes or otherwise degrades the special surface treatments of the working surfaces, which reduces their efficacy as the surgical procedure progresses.
It is also noted that, despite numerous advances in the field, currently-employed electrosurgical techniques often generate substantial smoke at the surgical site. Such smoke occurs as a result of tissue heating and the associated release of hot gases/vapor from the tissue site (e.g., in the form of an upward plume). As will be appreciated, any generation of smoke may impede observation of the surgical site during surgical procedures. Additionally, the generation of smoke results in attendant fouling of the atmosphere in the surgical theater. Clearly, these environmental impacts may adversely detract from the performance of medical personnel. Further, there is growing concern that the smoke may be a medium for the transport of pathogens away from the surgical site, including viruses such as HIV. Such concerns have contributed to the use of face shields and masks by surgical personnel.
To date, implemented approaches to deal with smoke have focused on the use of devices that either evacuate the smoke by sucking the same into a filtering system, or that merely blow the smoke away from the surgical site by a pressurized gas stream. Smoke evacuators typically require the movement of large amounts of air to be effective. As such, evacuators tend to be not only noisy but also space consuming. Approaches for blowing smoke away from the surgical site fail to address many of the above-noted concerns, since smoke is not actually removed from the surgical environment. Moreover, both of the above-noted approaches entail the use of added componentry, thereby increasing the cost and complexity of electrosurgical systems.